1. Field of the Invention
The present invention relates to a cutting insert and a face milling cutter with the cutting insert installed therein.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2008-006579 discloses an insert for a face milling cutter which is indexable and which includes cutting edges on the respective opposite sides thereof. The insert includes a major cutting edge located adjacent to a first relief face to allow chips to be removed and a secondary cutting edge located adjacent to a second relief face to allow surface cutting to be achieved. The major cutting edge forms an angle of 45° to an imaginary line in the direction of an extension of the secondary cutting edge. An intermediate cutting edge located adjacent to a third relief face between the first relief face and the second relief face is formed between the major cutting edge and the secondary cutting edge. The intermediate cutting edge is shorter than the major cutting edge and forms an angle smaller than 45° to the imaginary line. The intermediate cutting edge shifts to the adjacent major and secondary cutting edges via an arch-like partial cutting edge located adjacent to a protruding relief face. In the insert, an upper surface is generally at right angle to side surfaces and a lower surface is generally at right angle to the side surfaces.
Some inserts for face milling cutters include a relief face formed thereon and having a positive relief angle. In such an insert, for improved processing efficiency, it is important to improve the durability of cutting edges, and specifically to make the cutting edges unlikely to be chipped.